<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 100px;
            height: 100px;
            background-color: pink;
            text-align: center;
            margin: 100px auto;
            position: relative;
        }

        img {
            position: absolute;
            width: 100px;
            height: 100px;
            bottom: 0;
            left: 100px;
            display: none;
        }
        /* 鼠标经过div的时候img显示出来，和下拉菜单原理类似 */
        div:hover img{ 
            display: block;
        }
    </style>
</head>

<body>
    <div>
        二维码
        <img src="">
    </div>
</body>

</html>